llvm-project/llvm/lib/CodeGen/WasmEHPrepare.cpp

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//===-- WasmEHPrepare - Prepare excepton handling for WebAssembly --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This transformation is designed for use by code generators which use
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// WebAssembly exception handling scheme. This currently supports C++
// exceptions.
//
// WebAssembly exception handling uses Windows exception IR for the middle level
// representation. This pass does the following transformation for every
// catchpad block:
// (In C-style pseudocode)
//
// - Before:
// catchpad ...
// exn = wasm.get.exception();
// selector = wasm.get.selector();
// ...
//
// - After:
// catchpad ...
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// exn = wasm.extract.exception();
// // Only add below in case it's not a single catch (...)
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// wasm.landingpad.index(index);
// __wasm_lpad_context.lpad_index = index;
// __wasm_lpad_context.lsda = wasm.lsda();
// _Unwind_CallPersonality(exn);
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// selector = __wasm.landingpad_context.selector;
// ...
//
//
// * Background: Direct personality function call
// In WebAssembly EH, the VM is responsible for unwinding the stack once an
// exception is thrown. After the stack is unwound, the control flow is
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// transfered to WebAssembly 'catch' instruction.
//
// Unwinding the stack is not done by libunwind but the VM, so the personality
// function in libcxxabi cannot be called from libunwind during the unwinding
// process. So after a catch instruction, we insert a call to a wrapper function
// in libunwind that in turn calls the real personality function.
//
// In Itanium EH, if the personality function decides there is no matching catch
// clause in a call frame and no cleanup action to perform, the unwinder doesn't
// stop there and continues unwinding. But in Wasm EH, the unwinder stops at
// every call frame with a catch intruction, after which the personality
// function is called from the compiler-generated user code here.
//
// In libunwind, we have this struct that serves as a communincation channel
// between the compiler-generated user code and the personality function in
// libcxxabi.
//
// struct _Unwind_LandingPadContext {
// uintptr_t lpad_index;
// uintptr_t lsda;
// uintptr_t selector;
// };
// struct _Unwind_LandingPadContext __wasm_lpad_context = ...;
//
// And this wrapper in libunwind calls the personality function.
//
// _Unwind_Reason_Code _Unwind_CallPersonality(void *exception_ptr) {
// struct _Unwind_Exception *exception_obj =
// (struct _Unwind_Exception *)exception_ptr;
// _Unwind_Reason_Code ret = __gxx_personality_v0(
// 1, _UA_CLEANUP_PHASE, exception_obj->exception_class, exception_obj,
// (struct _Unwind_Context *)__wasm_lpad_context);
// return ret;
// }
//
// We pass a landing pad index, and the address of LSDA for the current function
// to the wrapper function _Unwind_CallPersonality in libunwind, and we retrieve
// the selector after it returns.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Triple.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/WasmEHFuncInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
#define DEBUG_TYPE "wasmehprepare"
namespace {
class WasmEHPrepare : public FunctionPass {
Type *LPadContextTy = nullptr; // type of 'struct _Unwind_LandingPadContext'
GlobalVariable *LPadContextGV = nullptr; // __wasm_lpad_context
// Field addresses of struct _Unwind_LandingPadContext
Value *LPadIndexField = nullptr; // lpad_index field
Value *LSDAField = nullptr; // lsda field
Value *SelectorField = nullptr; // selector
[WebAssembly] Make rethrow take an except_ref type argument Summary: In the new wasm EH proposal, `rethrow` takes an `except_ref` argument. This change was missing in r352598. This patch adds `llvm.wasm.rethrow.in.catch` intrinsic. This is an intrinsic that's gonna eventually be lowered to wasm `rethrow` instruction, but this intrinsic can appear only within a catchpad or a cleanuppad scope. Also this intrinsic needs to be invokable - otherwise EH pad successor for it will not be correctly generated in clang. This also adds lowering logic for this intrinsic in `SelectionDAGBuilder::visitInvoke`. This routine is basically a specialized and simplified version of `SelectionDAGBuilder::visitTargetIntrinsic`, but we can't use it because if is only for `CallInst`s. This deletes the previous `llvm.wasm.rethrow` intrinsic and related tests, which was meant to be used within a `__cxa_rethrow` library function. Turned out this needs some more logic, so the intrinsic for this purpose will be added later. LateEHPrepare takes a result value of `catch` and inserts it into matching `rethrow` as an argument. `RETHROW_IN_CATCH` is a pseudo instruction that serves as a link between `llvm.wasm.rethrow.in.catch` and the real wasm `rethrow` instruction. To generate a `rethrow` instruction, we need an `except_ref` argument, which is generated from `catch` instruction. But `catch` instrutions are added in LateEHPrepare pass, so we use `RETHROW_IN_CATCH`, which takes no argument, until we are able to correctly lower it to `rethrow` in LateEHPrepare. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59352 llvm-svn: 356316
2019-03-16 13:38:57 +08:00
Function *ThrowF = nullptr; // wasm.throw() intrinsic
Function *LPadIndexF = nullptr; // wasm.landingpad.index() intrinsic
Function *LSDAF = nullptr; // wasm.lsda() intrinsic
Function *GetExnF = nullptr; // wasm.get.exception() intrinsic
Function *ExtractExnF = nullptr; // wasm.extract.exception() intrinsic
Function *GetSelectorF = nullptr; // wasm.get.ehselector() intrinsic
[opaque pointer types] Add a FunctionCallee wrapper type, and use it. Recommit r352791 after tweaking DerivedTypes.h slightly, so that gcc doesn't choke on it, hopefully. Original Message: The FunctionCallee type is effectively a {FunctionType*,Value*} pair, and is a useful convenience to enable code to continue passing the result of getOrInsertFunction() through to EmitCall, even once pointer types lose their pointee-type. Then: - update the CallInst/InvokeInst instruction creation functions to take a Callee, - modify getOrInsertFunction to return FunctionCallee, and - update all callers appropriately. One area of particular note is the change to the sanitizer code. Previously, they had been casting the result of `getOrInsertFunction` to a `Function*` via `checkSanitizerInterfaceFunction`, and storing that. That would report an error if someone had already inserted a function declaraction with a mismatching signature. However, in general, LLVM allows for such mismatches, as `getOrInsertFunction` will automatically insert a bitcast if needed. As part of this cleanup, cause the sanitizer code to do the same. (It will call its functions using the expected signature, however they may have been declared.) Finally, in a small number of locations, callers of `getOrInsertFunction` actually were expecting/requiring that a brand new function was being created. In such cases, I've switched them to Function::Create instead. Differential Revision: https://reviews.llvm.org/D57315 llvm-svn: 352827
2019-02-01 10:28:03 +08:00
FunctionCallee CallPersonalityF =
[WebAssembly] Make rethrow take an except_ref type argument Summary: In the new wasm EH proposal, `rethrow` takes an `except_ref` argument. This change was missing in r352598. This patch adds `llvm.wasm.rethrow.in.catch` intrinsic. This is an intrinsic that's gonna eventually be lowered to wasm `rethrow` instruction, but this intrinsic can appear only within a catchpad or a cleanuppad scope. Also this intrinsic needs to be invokable - otherwise EH pad successor for it will not be correctly generated in clang. This also adds lowering logic for this intrinsic in `SelectionDAGBuilder::visitInvoke`. This routine is basically a specialized and simplified version of `SelectionDAGBuilder::visitTargetIntrinsic`, but we can't use it because if is only for `CallInst`s. This deletes the previous `llvm.wasm.rethrow` intrinsic and related tests, which was meant to be used within a `__cxa_rethrow` library function. Turned out this needs some more logic, so the intrinsic for this purpose will be added later. LateEHPrepare takes a result value of `catch` and inserts it into matching `rethrow` as an argument. `RETHROW_IN_CATCH` is a pseudo instruction that serves as a link between `llvm.wasm.rethrow.in.catch` and the real wasm `rethrow` instruction. To generate a `rethrow` instruction, we need an `except_ref` argument, which is generated from `catch` instruction. But `catch` instrutions are added in LateEHPrepare pass, so we use `RETHROW_IN_CATCH`, which takes no argument, until we are able to correctly lower it to `rethrow` in LateEHPrepare. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59352 llvm-svn: 356316
2019-03-16 13:38:57 +08:00
nullptr; // _Unwind_CallPersonality() wrapper
bool prepareEHPads(Function &F);
bool prepareThrows(Function &F);
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
void prepareEHPad(BasicBlock *BB, bool NeedLSDA, unsigned Index = 0);
void prepareTerminateCleanupPad(BasicBlock *BB);
public:
static char ID; // Pass identification, replacement for typeid
WasmEHPrepare() : FunctionPass(ID) {}
bool doInitialization(Module &M) override;
bool runOnFunction(Function &F) override;
StringRef getPassName() const override {
return "WebAssembly Exception handling preparation";
}
};
} // end anonymous namespace
char WasmEHPrepare::ID = 0;
INITIALIZE_PASS(WasmEHPrepare, DEBUG_TYPE, "Prepare WebAssembly exceptions",
false, false)
FunctionPass *llvm::createWasmEHPass() { return new WasmEHPrepare(); }
bool WasmEHPrepare::doInitialization(Module &M) {
IRBuilder<> IRB(M.getContext());
LPadContextTy = StructType::get(IRB.getInt32Ty(), // lpad_index
IRB.getInt8PtrTy(), // lsda
IRB.getInt32Ty() // selector
);
return false;
}
// Erase the specified BBs if the BB does not have any remaining predecessors,
// and also all its dead children.
template <typename Container>
static void eraseDeadBBsAndChildren(const Container &BBs) {
SmallVector<BasicBlock *, 8> WL(BBs.begin(), BBs.end());
while (!WL.empty()) {
auto *BB = WL.pop_back_val();
if (pred_begin(BB) != pred_end(BB))
continue;
WL.append(succ_begin(BB), succ_end(BB));
DeleteDeadBlock(BB);
}
}
bool WasmEHPrepare::runOnFunction(Function &F) {
bool Changed = false;
Changed |= prepareThrows(F);
Changed |= prepareEHPads(F);
return Changed;
}
bool WasmEHPrepare::prepareThrows(Function &F) {
Module &M = *F.getParent();
IRBuilder<> IRB(F.getContext());
bool Changed = false;
// wasm.throw() intinsic, which will be lowered to wasm 'throw' instruction.
ThrowF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_throw);
[WebAssembly] Make rethrow take an except_ref type argument Summary: In the new wasm EH proposal, `rethrow` takes an `except_ref` argument. This change was missing in r352598. This patch adds `llvm.wasm.rethrow.in.catch` intrinsic. This is an intrinsic that's gonna eventually be lowered to wasm `rethrow` instruction, but this intrinsic can appear only within a catchpad or a cleanuppad scope. Also this intrinsic needs to be invokable - otherwise EH pad successor for it will not be correctly generated in clang. This also adds lowering logic for this intrinsic in `SelectionDAGBuilder::visitInvoke`. This routine is basically a specialized and simplified version of `SelectionDAGBuilder::visitTargetIntrinsic`, but we can't use it because if is only for `CallInst`s. This deletes the previous `llvm.wasm.rethrow` intrinsic and related tests, which was meant to be used within a `__cxa_rethrow` library function. Turned out this needs some more logic, so the intrinsic for this purpose will be added later. LateEHPrepare takes a result value of `catch` and inserts it into matching `rethrow` as an argument. `RETHROW_IN_CATCH` is a pseudo instruction that serves as a link between `llvm.wasm.rethrow.in.catch` and the real wasm `rethrow` instruction. To generate a `rethrow` instruction, we need an `except_ref` argument, which is generated from `catch` instruction. But `catch` instrutions are added in LateEHPrepare pass, so we use `RETHROW_IN_CATCH`, which takes no argument, until we are able to correctly lower it to `rethrow` in LateEHPrepare. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59352 llvm-svn: 356316
2019-03-16 13:38:57 +08:00
// Insert an unreachable instruction after a call to @llvm.wasm.throw and
// delete all following instructions within the BB, and delete all the dead
// children of the BB as well.
for (User *U : ThrowF->users()) {
// A call to @llvm.wasm.throw() is only generated from __cxa_throw()
// builtin call within libcxxabi, and cannot be an InvokeInst.
auto *ThrowI = cast<CallInst>(U);
if (ThrowI->getFunction() != &F)
continue;
Changed = true;
auto *BB = ThrowI->getParent();
SmallVector<BasicBlock *, 4> Succs(succ_begin(BB), succ_end(BB));
auto &InstList = BB->getInstList();
InstList.erase(std::next(BasicBlock::iterator(ThrowI)), InstList.end());
IRB.SetInsertPoint(BB);
IRB.CreateUnreachable();
eraseDeadBBsAndChildren(Succs);
}
return Changed;
}
bool WasmEHPrepare::prepareEHPads(Function &F) {
Module &M = *F.getParent();
IRBuilder<> IRB(F.getContext());
SmallVector<BasicBlock *, 16> CatchPads;
SmallVector<BasicBlock *, 16> CleanupPads;
for (BasicBlock &BB : F) {
if (!BB.isEHPad())
continue;
auto *Pad = BB.getFirstNonPHI();
if (isa<CatchPadInst>(Pad))
CatchPads.push_back(&BB);
else if (isa<CleanupPadInst>(Pad))
CleanupPads.push_back(&BB);
}
if (CatchPads.empty() && CleanupPads.empty())
return false;
assert(F.hasPersonalityFn() && "Personality function not found");
// __wasm_lpad_context global variable
LPadContextGV = cast<GlobalVariable>(
M.getOrInsertGlobal("__wasm_lpad_context", LPadContextTy));
LPadIndexField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 0,
"lpad_index_gep");
LSDAField =
IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 1, "lsda_gep");
SelectorField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 2,
"selector_gep");
// wasm.landingpad.index() intrinsic, which is to specify landingpad index
LPadIndexF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_landingpad_index);
// wasm.lsda() intrinsic. Returns the address of LSDA table for the current
// function.
LSDAF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_lsda);
// wasm.get.exception() and wasm.get.ehselector() intrinsics. Calls to these
// are generated in clang.
GetExnF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_get_exception);
GetSelectorF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_get_ehselector);
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// wasm.extract.exception() is the same as wasm.get.exception() but it does
// not take a token argument. This will be lowered down to EXTRACT_EXCEPTION
// pseudo instruction in instruction selection, which will be expanded using
// 'br_on_exn' instruction later.
ExtractExnF =
Intrinsic::getDeclaration(&M, Intrinsic::wasm_extract_exception);
// _Unwind_CallPersonality() wrapper function, which calls the personality
[opaque pointer types] Add a FunctionCallee wrapper type, and use it. Recommit r352791 after tweaking DerivedTypes.h slightly, so that gcc doesn't choke on it, hopefully. Original Message: The FunctionCallee type is effectively a {FunctionType*,Value*} pair, and is a useful convenience to enable code to continue passing the result of getOrInsertFunction() through to EmitCall, even once pointer types lose their pointee-type. Then: - update the CallInst/InvokeInst instruction creation functions to take a Callee, - modify getOrInsertFunction to return FunctionCallee, and - update all callers appropriately. One area of particular note is the change to the sanitizer code. Previously, they had been casting the result of `getOrInsertFunction` to a `Function*` via `checkSanitizerInterfaceFunction`, and storing that. That would report an error if someone had already inserted a function declaraction with a mismatching signature. However, in general, LLVM allows for such mismatches, as `getOrInsertFunction` will automatically insert a bitcast if needed. As part of this cleanup, cause the sanitizer code to do the same. (It will call its functions using the expected signature, however they may have been declared.) Finally, in a small number of locations, callers of `getOrInsertFunction` actually were expecting/requiring that a brand new function was being created. In such cases, I've switched them to Function::Create instead. Differential Revision: https://reviews.llvm.org/D57315 llvm-svn: 352827
2019-02-01 10:28:03 +08:00
CallPersonalityF = M.getOrInsertFunction(
"_Unwind_CallPersonality", IRB.getInt32Ty(), IRB.getInt8PtrTy());
if (Function *F = dyn_cast<Function>(CallPersonalityF.getCallee()))
F->setDoesNotThrow();
unsigned Index = 0;
for (auto *BB : CatchPads) {
auto *CPI = cast<CatchPadInst>(BB->getFirstNonPHI());
// In case of a single catch (...), we don't need to emit LSDA
if (CPI->getNumArgOperands() == 1 &&
cast<Constant>(CPI->getArgOperand(0))->isNullValue())
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
prepareEHPad(BB, false);
else
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
prepareEHPad(BB, true, Index++);
}
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// Cleanup pads don't need LSDA.
for (auto *BB : CleanupPads)
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
prepareEHPad(BB, false);
return true;
}
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// Prepare an EH pad for Wasm EH handling. If NeedLSDA is false, Index is
// ignored.
void WasmEHPrepare::prepareEHPad(BasicBlock *BB, bool NeedLSDA,
unsigned Index) {
assert(BB->isEHPad() && "BB is not an EHPad!");
IRBuilder<> IRB(BB->getContext());
IRB.SetInsertPoint(&*BB->getFirstInsertionPt());
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
auto *FPI = cast<FuncletPadInst>(BB->getFirstNonPHI());
Instruction *GetExnCI = nullptr, *GetSelectorCI = nullptr;
for (auto &U : FPI->uses()) {
if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
if (CI->getCalledValue() == GetExnF)
GetExnCI = CI;
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
if (CI->getCalledValue() == GetSelectorF)
GetSelectorCI = CI;
}
}
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// Cleanup pads w/o __clang_call_terminate call do not have any of
// wasm.get.exception() or wasm.get.ehselector() calls. We need to do nothing.
if (!GetExnCI) {
assert(!GetSelectorCI &&
"wasm.get.ehselector() cannot exist w/o wasm.get.exception()");
return;
}
Instruction *ExtractExnCI = IRB.CreateCall(ExtractExnF, {}, "exn");
GetExnCI->replaceAllUsesWith(ExtractExnCI);
GetExnCI->eraseFromParent();
// In case it is a catchpad with single catch (...) or a cleanuppad, we don't
// need to call personality function because we don't need a selector.
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
if (!NeedLSDA) {
if (GetSelectorCI) {
assert(GetSelectorCI->use_empty() &&
"wasm.get.ehselector() still has uses!");
GetSelectorCI->eraseFromParent();
}
return;
}
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
IRB.SetInsertPoint(ExtractExnCI->getNextNode());
// This is to create a map of <landingpad EH label, landingpad index> in
// SelectionDAGISel, which is to be used in EHStreamer to emit LSDA tables.
// Pseudocode: wasm.landingpad.index(Index);
IRB.CreateCall(LPadIndexF, {FPI, IRB.getInt32(Index)});
// Pseudocode: __wasm_lpad_context.lpad_index = index;
IRB.CreateStore(IRB.getInt32(Index), LPadIndexField);
// Store LSDA address only if this catchpad belongs to a top-level
// catchswitch. If there is another catchpad that dominates this pad, we don't
// need to store LSDA address again, because they are the same throughout the
// function and have been already stored before.
// TODO Can we not store LSDA address in user function but make libcxxabi
// compute it?
auto *CPI = cast<CatchPadInst>(FPI);
if (isa<ConstantTokenNone>(CPI->getCatchSwitch()->getParentPad()))
// Pseudocode: __wasm_lpad_context.lsda = wasm.lsda();
IRB.CreateStore(IRB.CreateCall(LSDAF), LSDAField);
// Pseudocode: _Unwind_CallPersonality(exn);
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
CallInst *PersCI = IRB.CreateCall(CallPersonalityF, ExtractExnCI,
OperandBundleDef("funclet", CPI));
PersCI->setDoesNotThrow();
// Pseudocode: int selector = __wasm.landingpad_context.selector;
Instruction *Selector =
IRB.CreateLoad(IRB.getInt32Ty(), SelectorField, "selector");
// Replace the return value from wasm.get.ehselector() with the selector value
// loaded from __wasm_lpad_context.selector.
assert(GetSelectorCI && "wasm.get.ehselector() call does not exist");
GetSelectorCI->replaceAllUsesWith(Selector);
GetSelectorCI->eraseFromParent();
}
void llvm::calculateWasmEHInfo(const Function *F, WasmEHFuncInfo &EHInfo) {
[WebAssembly] Exception handling: Switch to the new proposal Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
2019-01-30 11:21:57 +08:00
// If an exception is not caught by a catchpad (i.e., it is a foreign
// exception), it will unwind to its parent catchswitch's unwind destination.
// We don't record an unwind destination for cleanuppads because every
// exception should be caught by it.
for (const auto &BB : *F) {
if (!BB.isEHPad())
continue;
const Instruction *Pad = BB.getFirstNonPHI();
if (const auto *CatchPad = dyn_cast<CatchPadInst>(Pad)) {
const auto *UnwindBB = CatchPad->getCatchSwitch()->getUnwindDest();
if (!UnwindBB)
continue;
const Instruction *UnwindPad = UnwindBB->getFirstNonPHI();
if (const auto *CatchSwitch = dyn_cast<CatchSwitchInst>(UnwindPad))
// Currently there should be only one handler per a catchswitch.
EHInfo.setEHPadUnwindDest(&BB, *CatchSwitch->handlers().begin());
else // cleanuppad
EHInfo.setEHPadUnwindDest(&BB, UnwindBB);
}
}
}